Tuberculosis is most often a disease of the lungs. It spreads from person to person when the person with TB disease coughs, sneezes or speaks, expelling bacteria into the air that others breathe. Untreated active tuberculosis is a serious and urgent public health threat. The Health Department acts quickly to treat cases of TB disease (to limit its spread) and to treat TB infection before it progresses to TB disease.

What is TB?

Tuberculosis is a bacterial infection which most often in the lungs, but it can appear in or spread to other parts of the body. Untreated, TB can destroy lung tissue and make breathing difficult or impossible. TB is a particular public health concern because it can spread easily through the air when a person with TB disease speaks, coughs or sneezes.

TB Infection

TB infection is more common than active TB disease. About one-third of the people in the world have TB infection. TB infection presents no symptoms, but requires treatment to prevent progression to TB disease.

A person must be exposed to (share air with) someone who has TB disease to become infected. Not everyone that is exposed becomes infected. Those that do become infected cannot spread TB to others unless their infection progresses to TB disease.

TB infection can be treated to reduce the chance that the infection will progress to TB disease. TB Infection usually progresses to disease when the immune system of the infected person weakens, as a result of illness, age, medication or other causes. While TB infection is not contagious, it is very important to identify and treat infection before it can advance to TB disease. Since a person with TB infection has no signs or symptoms and does not feel sick, the only way to know whether you are infected is to have a TB test.

Co-Infections: Who Is at Risk

Smoking or chronic diseases such as HIV and diabetes increase the chances that you will contract
tuberculosis,
and that it will progress more rapidly to serious or fatal illness. Also, some medications used to treat diseases such as arthritis, Crohn's disease, psoriasis, and several other autoimmune disorders can greatly increase the risk of an infected person progressing to TB disease if not treated.
Knowing your TB test status is essential.

TB Disease

Active TB disease is less common than TB infection but is serious and can be spread to others.

A person with TB disease typically is sick or has symptoms unless diagnosed early. Common symptoms include weight loss, loss of appetite, night sweats, cough, weakness and fatigue.
TB disease can be spread to others by extended contact (sharing air with the person who has TB). If not treated correctly, TB disease can cause serious illness and death.

TB Exposure

For a person to become infected a fairly long or repeated exposure is often required. The people most likely to become infected are contacts to (people who share air with) a person who has TB disease and persons living in or traveling to countries where TB is prevalent.

An estimated 10-15 million U. S. residents and one-third of the world’s population are currently infected with TB. A blood test called an Interferon Gamma Release Assay (IGRA) is the preferred test to identify TB infection.

Is TB infection dangerous?

The danger of TB infection is not knowing that you have it. If left untreated, TB infection can progress to TB disease, which can be fatal. TB infection does not cause sickness and has no symptoms. Persons with TB infection cannot spread the disease to others. A skin test or blood test can detect the presence of TB infection.